The mechanical coupling of shaft elements is well known and many couplings of various design have been invented. Most such couplings require substantially unrestricted access to the shafts to be connected.
Certain equipment such as precision sizing machines for separating free flowing granular materials by particle size or width and thickness require quick disconnect couplings which are functional in a very restricted space available within the machine housing. Particle sizers are widely used in the food, seed and plastics industries for sorting, cleaning and sizing granular materials such as seeds, pellets and particles. In order to provide versatile machinery, particle sizers are constructed to accommodate interchangeable sizing drums. Materials are sorted by passing material through perforated drums which permits undersized materials to drop through the perforations. A series of drums permit the separation of granular materials into several size grades. It also permits the cleaning of food stuffs such as cereal grains and the like. The drums in a precision sizer are typically supported on one end by a roller arrangement and on the opposite end by a driven shall connected to the drum. A coupling is required at the driven shaft end for transmitting rotational torque to the driven shaft and for supporting the driven shall and the drum. Although precision sizers have been in widespread use for more than 100 years, a simple coupling which is easily operated in the confined space available within the sizer cabinet and which permits a rapid change of drums as well as reliable operation has not, heretofore, been invented.
Many coupling devices have been invented but most are not suitable for use in the restricted space available in a precision sizer machine. U.S. Pat. No. 4,943,182 entitled RAPID FASTENER OF THE BAYONET TYPE to Hoblingre is typical of an inventive concept useful for connecting certain drive shafts but unsuitable for use in an application where the driven shaft must be lifted in a lateral direction away from the drive shaft without any axial movement of either shaft. While solutions to this problem have been sought, all couplings used in precision sizing machines known to date have been complicated, expensive to manufacture and more or less difficult to use.